TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Immune Response Of Atlantic Salmon To Particulate-Adsorbed Extracellular Proteins of Aeromonas salmonicida Rocco C. Cipriano and Chris Ottinger U.S. Geological Survey/BRD, National Fish Health Research Laboratory, 1700 Leetown Road, Kearneysville WV, 25430 Prevention of furunculosis in salmonids may be achieved by vaccination with the extracellular proteins (ECP) produced by Aeromonas salmonicida. Typically, these soluble immunogens are delivered by intraperitoneal (IP) injection with an oil-based adjuvant. As an alternative approach to immunogen delivery, we have evaluated the potential of particulate-adsorbed A. salmonicida ECP to induce protective immunity in Atlantic salmon. Fish vaccinated IP with ECP adsorbed on DEAE-Sephadex A25 were challenged by bath or effluent exposure eight weeks post vaccination. The impact of the vaccine was compared to buffer and/or carrier controls with data expressed as percent mortality (effluent exposure) or the number of colony forming units (CFU) per unit mass of kidney tissue or mucous (bath exposure). Groups of Atlantic salmon immunized with adsorbed ECP demonstrated significant lower mortality than controls. Significant reductions in and the number of isolated A. salmonicida CFU were also observed with significant tissue specific changes in pathogen loads observed between groups of fish sampled day 5 versus day 8 post exposure. Vaccination of Atlantic salmon with adsorbed ECP clearly provides protection against furunculosis. However, we have little information on the underlying immune mechanisms by which the protection is achieved. We are now evaluating these processes and will report our progress to date. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page